i have install the silverstripe v2.4.7 in linux, and it is working fine.
but now i want to install image gallery module,
that Dataobjectmanager,imagegallery, swfupload i have downloaded in the www.silverstripe.org

After that i have extracted the Dataobjectmanager,imagegallery,swfupload tar file , and i put it in to root folder,that is
my application folder var/www/silverstripe/.
after this i have logined into admin module and i tryed so many type in the url
a) /dev/build/?flush=1

b) /dev/build?flush=1

c) /dev/build?flush=all

but i am getting error like The action dev/build is not in the class CMSMAIN

Please give me the solution for this as soon as possible

Thank u very much for giving the solution to my previous problem.

Now the thing is

Step 1: I copied my dataobject_manager folder in to my application root folder
Step 2: I went to browser and typed in the url like http://yoursite.com/dev/build/?flush=1

It gives the below para in the Blue color, and the remaining lines in the black color and green color.

File
Field File.ClassName: changed to enum('File','FLV','MP3','Image','Folder','Image_Cached') character set utf8 collate utf8_general_ci default 'File' (from enum('File','Image','Folder','Image_Cached') character set utf8 collate utf8_general_ci default 'File')
Field File.SortOrder: created as int(11) not null default 0

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Step 3: I copied my swfupload folder in to my application root folder
Step 4: I went to browser and typed in the url like http://yoursite.com/dev/build/?flush=1

It gives every line in the black color.

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Step 5: I copied my image_gallery folder in to my application root folder
Step 6: I went to browser and typed in the url like http://yoursite.com/dev/build/?flush=1

It gives the below para in the Blue color, and the remaining lines in the black color and green color.

SiteTree
Field SiteTree.ClassName: changed to enum('SiteTree','Page','ImageGalleryPage','ErrorPage','RedirectorPage','VirtualPage') character set utf8 collate utf8_general_ci default 'SiteTree' (from enum('SiteTree','Page','ErrorPage','RedirectorPage','VirtualPage') character set utf8 collate utf8_general_ci default 'SiteTree')

Field SiteTree_Live.ClassName: changed to enum('SiteTree','Page','ImageGalleryPage','ErrorPage','RedirectorPage','VirtualPage') character set utf8 collate utf8_general_ci default 'SiteTree' (from enum('SiteTree','Page','ErrorPage','RedirectorPage','VirtualPage') character set utf8 collate utf8_general_ci default 'SiteTree')

Field SiteTree_versions.ClassName: changed to enum('SiteTree','Page','ImageGalleryPage','ErrorPage','RedirectorPage','VirtualPage') character set utf8 collate utf8_general_ci default 'SiteTree' (from enum('SiteTree','Page','ErrorPage','RedirectorPage','VirtualPage') character set utf8 collate utf8_general_ci default 'SiteTree')

File
Field File.ClassName: changed to enum('File','FLV','MP3','Image','Folder','ImageGalleryImage','Image_Cached') character set utf8 collate utf8_general_ci default 'File' (from enum('File','FLV','MP3','Image','Folder','Image_Cached') character set utf8 collate utf8_general_ci default 'File')

at the end it gives Database build completed!
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After this i login to my admin

step 1: I select the image gallery page in the dropdown list and i clicked on the go button

But it giving error like "error loading page"

Please give me the solution for this problem, i am waiting for your reply.